From patchwork Wed Sep 18 13:19:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11150369 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 01C7813BD for ; Wed, 18 Sep 2019 13:20:25 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D4146206C2 for ; Wed, 18 Sep 2019 13:20:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hhOHLsMS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D4146206C2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=QdtZSwuS25S/hUo+7Io15loCA+D/C1XABQZVpKjiv6I=; b=hhOHLsMSk7XH504bHJYTYgYVzq nleGBqOYhtXupK4bCowXkyQ44aVNYVvlAyUCCvu8cKdebQtAhw2lWzdsAHJcbR7OIswSPiEgtaCk7 4kpCehjd7vZhg7tkddWTi1B/Jej7qf1SrjeIzEFlH0tzGo1l1dXwTj91WrBnZ7oPbceV6ILBZkbNa AktzT1DHzv6LHjmi360HLR47eNWSMpCYNUZKRLpfSs1pQ8K+2VPK9lCam+dbKCbu4WzmldwN2J8Hb DFae4lmi5PJORK0i3LhLbXOG2p4HpQiS22ZlN9vwpcbfWyq1hmlMzeWML9DUsfSGik2fz3cpHHFc6 +p02OM2g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iAZsN-0005Z6-5I; Wed, 18 Sep 2019 13:20:07 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iAZrx-0004nK-PP for linux-arm-kernel@lists.infradead.org; Wed, 18 Sep 2019 13:19:43 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 73C301596; Wed, 18 Sep 2019 06:19:40 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 28B583F575; Wed, 18 Sep 2019 06:19:34 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Subject: [PATCH v4 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Date: Wed, 18 Sep 2019 21:19:13 +0800 Message-Id: <20190918131914.38081-3-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190918131914.38081-1-justin.he@arm.com> References: <20190918131914.38081-1-justin.he@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190918_061941_917905_FE2568B3 X-CRM114-Status: GOOD ( 10.90 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ralph Campbell , Jia He , Andrew Morton , Anshuman Khandual , Jun Yao , Kaly Xin , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Punit Agrawal , hejianet@gmail.com, Thomas Gleixner , Robin Murphy , Alex Van Brunt MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org On arm64 without hardware Access Flag, copying fromuser will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64. Hence implement arch_faults_on_old_pte on arm64 to indicate that it might cause page fault when accessing old pte. Signed-off-by: Jia He --- arch/arm64/include/asm/pgtable.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e09760ece844..4a9939615e41 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -868,6 +868,18 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, #define phys_to_ttbr(addr) (addr) #endif +/* + * On arm64 without hardware Access Flag, copying fromuser will fail because + * the pte is old and cannot be marked young. So we always end up with zeroed + * page after fork() + CoW for pfn mappings. we don't always have a + * hardware-managed access flag on arm64. + */ +static inline bool arch_faults_on_old_pte(void) +{ + return !cpu_has_hw_af(); +} +#define arch_faults_on_old_pte arch_faults_on_old_pte + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */